The present invention is directed to a method of forming photoresist patterns having micron and submicron dimensions These photoresists find use in fabrication of complex structures such as those in electronic devices and magnetic thin film heads. The present invention also is directed to unique photoresist compositions that are capable of being used in the present method. The present invention also describes various organometallic reagents that are useful in the present method.
Many of the recent advancements in electronic devices and components have resulted from improvements in manufacturing techniques. Some of the most important improvements have occurred in microlithography and in methods of transferring the patterns used to create the complex structures within the electronic devices.
One of the preferred methods of transferring patterns of micron and submicron dimensions is dry etching. This method utilizes plasma or reactive ion etching to remove specific areas of material on a surface so that a pattern remains. In many instances, this method of pattern creation has replaced older processes which used solvent development of a material to create the pattern. These wet processing techniques frequently did not permit the dimensional control desired in the creation of micron and submicron dimensional patterns.
Typically, the material to be dry etched to create a pattern is a polymeric material for reasons of ease of use, material properties and cost considerations. When an organic polymer is used, dry etching can be done using an oxygen plasma or oxygen reactive ion etching.
During oxygen plasma and/or oxygen reactive ion etching, the organic content of a polymer is converted to a gaseous form which is easily removed. In order to create the desired pattern, there must be some areas of the polymeric material which are made resistant to the etching materials, and other areas which are not reactive therewith.
One method of producing such an etch-resistant polymeric material is to utilize a polymeric resist material containing silicon in a sufficiently large quantity so that exposure to oxygen plasma, for example, results in formation of silicon oxides, which form a protective layer and prevent the conversion of the polymer to its gaseous form.
Examples of silicon-containing copolymers, comprising a compound containing an acrylate moiety and a silicon containing oxime ester of methacrylic acid, which act as a positive resist and which can be dry developed are disclosed in U.S. Pat. No. 4,433,044 to Meyer et al.
A method of selectively removing a portion of a layer of material on a substrate by oxygen plasma etching, utilizing a mask of resist material comprising a poly (silane sulfone) copolymer is disclosed in U.S. Pat. No. 4,357,369 to Kilichowski et al. A method of producing solid state devices by dry etching of a resist film comprising a silicon-containing or nonsilicon-containing but organometallic monomer-containing polymer is described in U.S. Pat. No. 4,396,704 to Taylor.
Another method for forming a micropattern using a technique similar to those set forth above is disclosed in U.S. Pat. No. 4,430,153 to Gleason et al. The method involves forming an etch barrier in the reactive ion etching of an aromatic polyamic acid/imide polymer.
Another method for forming a micropattern using a technique similar to those above is disclosed in U.S. Pat. No. 4,426,247 to Tamamura et al.
Recently, processes have been developed which permit selective conversion of portions of a non-silicon-containing resist to a silicon-containing etch-resistant resist The non-silicon-containing resist is exposed to patterned radiation to create a latent image within the resist. Examples of this method of obtaining dry-developable multilayer resists are described in U.S. Pat. No. 4,552,833.
In U.S. Pat. No. 4,613,398 to Chiong et al., there is described a method for producing oxygen etch-resistant polymeric films which incorporate a protective oxide-forming metal permeated into the polymer. These films are useful as positive tone resist patterns for use with dry development techniques.
The present invention represents yet another advance in this art.